1. Field of the Invention
The present invention relates to a solid-state imaging device, a method for manufacturing the solid-state imaging device, and an imaging apparatus.
2. Description of the Related Art
Regarding a solid-state imaging device, e.g., a CMOS sensor, including a pixel portion provided with a photoelectric conversion portion, which photoelectrically converts incident light to obtain an electric signal, and a peripheral circuit portion disposed on the periphery of the pixel portion, in a semiconductor substrate, a gate insulating film of the peripheral circuit portion (logic element portion) has become thinner as the element has become finer. Along with that, an increase in tunnel current of the gate insulating film becomes a problem. In the MOS transistor technology, a silicon oxynitride film is used as the gate insulating film in order to suppress a tunnel current of the gate insulating film (refer to, for example, Japanese Patent No. 3752241).
In the case where a logic transistor, which includes a silicon oxynitride film serving as a gate insulating film of an element (MOS transistor) disposed in the peripheral circuit portion of the CMOS sensor, is applied, it is desirable that the performance of the CMOS sensor does not deteriorate.
In addition, as shown in FIG. 46, if a gate insulating film 31 composed of a silicon oxynitride film remains on a photoelectric conversion portion (for example, photodiode) 21, there is a problem in that deterioration in white defect occurs because of a fixed charge in the gate insulating film 31.
Furthermore, as shown in FIG. 47, regarding an antireflection film just above a photoelectric conversion portion (for example, photodiode) 21, since a three layer structure (not shown in the drawing) of silicon oxide film/silicon nitride film/silicon oxide film becomes a multiple structure of silicon oxide (SiO2) film/silicon nitride (SiN) film/silicon oxide (SiO2) film/silicon oxynitride film, the light undergoes multiple reflection and the ripple property in dispersion of light deteriorates. Moreover, since the ripple property deteriorates, a problem occurs in that variations in dispersion of light increase between chips.
In addition, there is a problem in that optimization becomes complicated because of a multiple structure.